Maintaining The Rheodyne 7725I Manual Injector; Tightening The Needle Seal - Waters 600E Installation And Maintenance Manual

4.4 Maintaining the Rheodyne 7725i Manual Injector

Note: The Rheodyne 7725i manual injector is optional. If it is not installed on your system,
ignore this section.
The Rheodyne 7725i manual injector requires minimal maintenance. With normal use, the
injector should perform thousands of cycles without fail.
This section describes the following maintenance procedures:
•

Tightening the needle seal

• Replacing the position sensing switch
• Rotor seal leakage
Refer to Figure 4-19
4.4.1 Tightening the Needle Seal
The needle seal, a Teflon sleeve in the rotor seal, may not seal correctly around a needle
that is smaller than average. A poor seal results in a loss of accuracy in sample loading.
To reform the Teflon sleeve to make a good seal:
• Remove the needle from the needle port.
• Push gently on the plastic needle guide with the eraser end of a pencil. Do not
squash the Teflon sleeve. Repeat if necessary.
STOP
1. Fill the syringe with water. Place the injector in the Load position and slowly
discharge the water in the syringe into the injector. Notice the lack of resistance to
syringe discharge.
2. Repeat step 1 with the injector handle halfway between Load and Inject (the pump
must be off). The resistance to discharging the syringe should now be much greater.
The needle seal holds only a few psi of pressure, and will not completely prevent syringe
discharge with the handle in the halfway position.
for each procedure.
Attention: Always use the correct type and gauge needle to load the
injector, or damage to the rotor seal may result.
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